Transistors used in electronic circuits are constantly subjected to current and voltage stress. For example, transistors coupled to a high voltage source may experience current and voltage stress when being switched from a low voltage source (VccL) to the high voltage source (VccH).
When subjected to swings in voltage, a transistor may experience breakdown across the transistor's junctions. For example, PMOS (P-type metal oxide semiconductor) and NMOS (N-type metal oxide semiconductor) transistors, that include a thin silicon oxide layer separating the gate from the channel, may experience breakdown at the oxide layer due to extreme voltage or current stress caused by input voltage swings. If the voltage at the junction exceeds the breakdown voltage of the PMOS or NMOS transistor, the transistor will eventually fail.